2017 AP Chemistry Final Exam Kaylie, Demi, Brooke, Laura
When 4 L of He, 6 L of N2 and 10 L of Ar, all at 0 C and 1 atm, are pumped into an evacuated 8 L rigid container, the final pressure in the container at 0 is
2.5 atm
When 5 g of NH4ClO4 is added to 100 ml of water in a calorimiter, the temperature of teh solution formed decreases by 3 C. if 5 g of NH4ClO4 is added to 1000 mL of water in a calorimeter initially at 25 C, the final temperature of the solution will be approximately
24.7 C
(22) If P(N2O4) is 1.33 atm when the system is at equilibrium at 70 C which is P(NO2)
2 atm
(11) To determine the number of moles of Cu in the sample of the mixture, the students measured the absorbance of known concentrations of CuNO3 using a spectrophotometer
the student labelled the cuvettes incorrectly, reversing the labels of the solutions of known concentrations
(13) In one student's experiment the reaction proceeded at a much slower rate than it did in the other student's experiments
the student used a 1.5M solution of HNO3 instead of 15.8 solution of HNO3
(43) What is the value of the enthalpy change per mole of HCl (g) produced
-93 kJ
(38) Based on the thermodynamic data, which of the following is true at 298 K
0<k<1
(58) A 0.35 g sample of Li (s) is placed in an Erlenmeyer flask containing 100 mL of water at 25 C. A balloon is places over the mouth of the flask to collect the hydrogen gas that is generated. After all of the Li (s) has reacted with H2O (l), the solution in the flask is added to a clean, dry buret and used to titrate an aqueous solution of a monoprotic acid. The pH curve for this titration is shown in the diagram below. Which of the following is the balanced net ionic equation for the reaction between Li (s) and water?
2Li (s) + 2 H2O --> 2 Li + (aq) + 2 OH- (aq) +H2 (g)
(37) Based on the bond energies listed in the table above, which of the following is closest to the bond energy of the C-N bond
300kj/mol
(12) The students determined that the reaction produced .01 mol of CuNO3.
32%
(26)The reactions above are carried out in sealed rigid containers and allowed to reach equilibrium. if the volume of the container is reduced from 1 L to .5 L at constant temperature, for which of the reactions will the amount of products be increased
4HCL + O2 --> 2 Cl2 + 2H2O
(5) If the absorbance of the mixture is .2 at 453 nm how many moles of Fe were present in the 100 ml sample
4x10^-6
(57) A 0.35 g sample of Li (s) is placed in an Erlenmeyer flask containing 100 mL of water at 25 C. A balloon is places over the mouth of the flask to collect the hydrogen gas that is generated. After all of the Li (s) has reacted with H2O (l), the solution in the flask is added to a clean, dry buret and used to titrate an aqueous solution of a monoprotic acid. The pH curve for this titration is shown in the diagram below. On the basis of the pH curve, the pKa value of the acid is closest to.....
5
(35) Which of the following particle views best represents the mixture when the titration is halfway to the equivalence point?
5 H2O2 ions and 2 Mn ions
ClO 2- (aq) +HCOOH (aq) <-> HClO2 (aq) + HCOO- (aq) Keq < 1 What are the relative strengths of the acids and bases in the reaction represented by the equation above?
Acid Strength: HClO2 > HCOOH Base Strength: ClO2 - < HCOO-
Ag + (aq) +NH3 <-> AG(NO3)+ (aq) Keq1 = 2E3 Ag(NH3)+ (aq) +NH3 <-> Ag(NH3)2 + Keq2 = 8E3 Equal volumes of 0.1M Ag(NO3) (aq) and 2.0M NH3 (aq) are mixed and the reactions above occur. Which Ag species will have the highest concentration in the equilibrium system shown below, and why? Ag+ (aq) + 2NH3 (aq) <-> Ag(NH3)2 + (aq) . Keq3=?
Ag(NH3)2 + (aq), because Keq3 =1.6E7
(6) The first ionization energy of an element is the energy required to remove an electron form a gaseous atom of an element
Al + Mg --> Al + Mg
2H2O2 (l) -> 2H2O(l) + O2(g) The exothermic process represented above is best classified as a... ? :( :/
Chemical change, because covalent bonds are broken and new covalent bonds are formed
An acetate buffer solution is prepared by combining 50mL of 0.2M acetic acid, HC2H3O2(aq), and 50mL of 0.2M sodium acetates NaC2H3O2(aq). A 5.0mL sample of 0.1M NaOH (aq) is added to the buffer solution. Which of the following is the correct pairing of the acetate species present in greater concentration and of the pH of the solution after the NaOH (aq) is added (the pKa of acetic acid is 4.7)
C2H3O2-, pH > 4.7
The compound CCl4 is nonflammable and was once commonly used in fire extinguishers. On the basis of periodic properties, which of the following compounds can most likely be used as a fire resistant chemical
CBr4
(31)Based on the information in the table above, which of the following shows the cell potential and gibbs free energy change for the overall reaction that occurs in a standard galvanic cell
Ecell = 1.63, G = -944
(19) The complete photo electron spectra of neutral atoms of two unknown elements, X and Y are shown above. Which of the following can be inferred from the data
Element Y has a greater nuclear charge when element X does
(34) The process of dissolution of NaCL isH2O is represented in the diagram above. Which of the following summarizes the signs of H and S for each of teh dissolution process
H+ S+, H+ S+, H- S-
(32) Which of the following mechanisms for the catalyzed reaction is consistent with the equation and diagram above?
O3 + NO --> NO2 + O2
A student prepares a solution by combing 100mL of 0.3M HNO2(aq) and 100mL of 0.3M KNO2(aq). Which of the following equations represents the reaction that best helps to explain why adding a few drops of 1.0M HCL(aq) does not significantly change the Ph of the solution?
H+(aq) +NO2-(aq) -> HNO2 (aq)
(51) Which of the following is the strongest type of interaction that occurs between the atoms within the circled areas of the two molecules represented above
H-Bond
which of the following has the bonds arranged in order of decreasing polarity
H-F>N-F>F-F
(25) Which of the following statements about H for the reaction is correct
H>0 because energy is required to break the N-N bond
Ne, HF, C2H6, CH4 Which of the substances listed above has the highest boiling point, and why?
HF, because its molecule form hydrogen bonds
(10) Each student in a class is placed a 2 g sample of a mixture of CU and AL in fume hood. The students slowly poured 15 ml of 15.8M HNO3 into their beakers
It is a redox reaction, because CU is oxidized and the nitrogen atom in NO3 is reduced
(45) Based on the information above, which of the following expressions represents the equilibrium constant, K, for the reaction represented by the equation below La 3+ + CO3 2- <-> La CO3+
K=(K1)(Kw)/(Ka)
(8) Based on the diagram above, which of the following best helps to explain why MgO is not able to conduct electricity, but MgO is a good conductor of electricity
MgO consists of separate Mg ions and O ions held in a fixed lattice, but in MgO the ions are free to move and conduct electricity
The ideal gas law best describes the properties of which of the following gases
N2
on the basis of molecular structure and bond polarity, which of the following compounds is most likely to have the greatest solubility in water
NH3
If a pure sample of an oxide of sulfur contains 40 percent sulfur and 60 percent oxygen by mass, then the empirical formula of the oxide is
SO3
(56) A 0.35 g sample of Li (s) is placed in an Erlenmeyer flask containing 100 mL of water at 25 C. A balloon is places over the mouth of the flask to collect the hydrogen gas that is generated. After all of the Li (s) has reacted with H2O (l), the solution in the flask is added to a clean, dry buret and used to titrate an aqueous solution of a monoprotic acid. The pH curve for this titration is shown in the diagram below. What will be the effect on the amount of gas produced if the experiment is repeated using 0.35 g K(s) instead of 0.35 g Li (s)?
Some gases will be produced but less than the amount of gas produced with Li (s)
(59) Benzene, C6H6, has a structure shown above, considering the observation that benzene is only sparingly soluble in water, which of the following best described the intermolecular forces of attraction between water and benzene.
The dipole-induced dipole and LDF between water and benzene
2H2 (aq) + O2 (g) --> 2H20 (g) When H2 (g) and O2 (g) are mixed together in a rigid reactio vessel at 25 C, no reaction occurs. When the mixture is sparked, however, the gases react vigorously according to the equation above, releasing heat. Which of the following statements correctly explains why the spark is needed of the reaction to occur when the gases are originally at 25 C?
The reaction has a large activation energy at 25 C.
(54) 2XY (g) <-> X2 (g) + Y2 (g) . Kp =230 A certain gas, XY (g), decomposes as represented by the equation above. A sample of each of the three gasses is put in a previously evacuated container. The initial partial pressures of the gases are shown in the table below XY . 0.010 X2 . 0.20 Y2 . 2.0 The temperature of the reaction mixture is held constant. in which direction will the reaction proceed?
The reaction will form more reactant
(55) A 0.35 g sample of Li (s) is placed in an Erlenmeyer flask containing 100 mL of water at 25 C. A balloon is places over the mouth of the flask to collect the hydrogen gas that is generated. After all of the Li (s) has reacted with H2O (l), the solution in the flask is added to a clean, dry buret and used to titrate an aqueous solution of a monoprotic acid. The pH curve for this titration is shown in the diagram below. Which of the following changes will most likely increase the rate of the reaction between Li(s) and water?
Using a 0.35 g sample of Li(s) cut into smaller pieces
(39) Three saturated solution are prepared at 25 C based on the information in teh table above, which of the following lists the solutions in order of increasing Ag
Z<X<Y
(1) The mass spectrum of an average sample of a pure element is shown in the figure above
Zr
(30) NH3 reacts with BF3 to form a single species. which of the folloing structural diagrams is the most likely representation of the product of the reaction.
[3H on N connected with 3F on B]
(9) A mixture of CO and O is placed in a container, as shown above. A reaction occurs, forming CO2. Which of the following best represents the contents of the box after the reaction has proceeded as completely as possible
[4-3 molecule, 1-2 molecule]
(7) In the reaction represented above, what is the hybridization of the C atoms before and after the reaction occurs
before sp^2 after sp^3
(20) Based on structures shown above, which of the following statements identifies the compound with the higher boiling point and provides the best explanation for the higher boiling point
compound 2, because it forms hydrogen bonds, whereas compound 1 does not
Mg(OH)2 (s) <-> Mg 2+ (aq) + 2OH- (aq) The exothermic dissolution of Mg(OH)2 (s) in water is represetnted by the equation above. The Ksp of Mg(OH)2 is 1.8E-11. Which of the following changes will increase the solubility of Mg(OH)2 in an aqueous solution
decreaseing the pH
at 298k and 1 atm, Br2 is a liquid with a high vapor pressure, and Cl2 is a gas
forces among Br2 molecules are stronger than those among Cl2 molecules
A student is given a sample of a pure, white crystalline substance. Which f the following would be most useful in providing data at determine if the substance is an ionic compound
testing the electrical conductivity of an aqueous solution of the substance
(36) Under which of the following temperature conditions is the reaction thermodynamically favored?
it is not favored with any temperature
(24) Which of the following best predicts how the partial pressures of the reacting species will be affected if a small amount of Ar(g) is added to the equilibrium mixture at constant volume
no change will take place
(28) Which of the following is the rate law for the overall reaction that is consistent with the proposed mechanism
rate = K[NO2]2
(60) Acid dissociation constants of two acids are listed int eh table above. A 20mL sample of 0.1M solution of each acid is titrated to the equivalence point with 20mL of 0.1M NaOH. Which of the following is a true statement about the pH of the solutions at the equivalence point?
solution 1has a higher pH at the equivalence point because CH3CO2H has a stronger conjugate base.
(27)The table above provides some information about 2 types of steel, both of whihc are alloys of iron and carbon. Which of the folloinw best helps to explain why high-carbon steel is more rigid than low carbon steel
the additional carbon atoms within the alloy make it more difficult for the iron atoms to slide past one another
(41) For the system repressed above, O2 and O3 initially are .15mol/L and 2.5 mol/L respectively. Which of the following best predicts what will occur as the system approaches equilibrium at 570K
the amount of O3 will decrease because Q>Kc
(23) Which of the following statements best helps to explain why the contents of the tube containing the equilibrium mixture turned a lighter color when the tube was placed into an ice bath
the forward reaction is endothermic
Cl-(aq) +ClO-(aq) + 2H+(aq) --> Cl2(g) + H2O(l) What effect will increasing H at constant temperature have on the reaction represented above?
the frequency of collision between H ions and CLo ions will increase
(33) The equilibrium system represented by the equation above initially contains equal concentrations of Cr2O7 and CrO4. Which of the folloinf statements correctly predicts the result of adding a sample of 6M NaOH to the system, and provides an explanation
the mixture will become more yellow because Oh will shift the equilibrium toward products
A sample of a solid labeled as NaCl may be impure. a student analyzes the sample and determines that it contains 75 percent chlorine by mass. Pure NaCl contains 61 percent chlorine by mass
the sample contains NaCl and LiCl
(42) Which of the following statement identifies the greates single reasont aht the value of Kp for the overall reaction 298 k has such a large magnitude
the value of H for the overall reaction is large and negative
